Role of endogenous psychosine accumulation in oligodendrocyte differentiation and survival: implication for Krabbe disease.

Krabbe disease is a lethal, demyelinating condition caused by genetic deficiency of galactocerebrosidase (GALC) and resultant accumulation of its cytotoxic substrate, psychosine (galactosylsphingosine), primarily in oligodendrocytes (OLs). Psychosine is generated by galactosylation of sphingosine by UDP-galactose:ceramide galactosyltransferase (CGT), a galactosylceramide synthesizing enzyme which is primarily expressed in OLs. The expression of CGT and the synthesis of galactosyl-sphingolipids are associated with the terminal differentiation of OL, but little is known about the participation of endogenous psychosine accumulation in OL differentiation under GALC deficient conditions. In this study, we report that accumulation of endogenous psychosine under GALC deficient Krabbe conditions impedes OL differentiation process both by decreasing the expression of myelin lipids and protein and by inducing the cell death of maturating OLs. The psychosine pathology under GALC deficient conditions involves participation of secretory phospholipase A2 (sPLA2) activation and increase in its metabolites, as evidenced by attenuation of psychosine-induced pathology by treatment with pharmacological inhibitor of sPLA2 7,7-dimethyleicosadienoic acid (DEDA). These observations suggest for potential therapeutic efficacy of sPLA2 inhibitor in Krabbe disease.

Inhibition of rho family functions by lovastatin promotes myelin repair in ameliorating experimental autoimmune encephalomyelitis.

Impaired remyelination is critical to neuroinflammation in multiple sclerosis (MS), which causes chronic and relapsing neurological impairments. Recent studies revealed that immunomodulatory activity of statins in an experimental autoimmune encephalomyelitis (EAE) model of MS are via depletion of isoprenoids (farnesyl-pyrophosphate and geranylgeranyl-pyrophosphate) rather than cholesterol in immune cells. In addition, we previously documented that lovastatin impedes demyelination and promotes myelin repair in treated EAE animals. To this end, we revealed the underlying mechanism of lovastatin-induced myelin repair in EAE using in vitro and in vivo approaches. Survival, proliferation (chondroitin sulfate proteoglycan-NG2(+) and late oligodendrocyte progenitor marker(+)), and terminal-differentiation (myelin basic protein(+)) of OPs was significantly increased in association with induction of a promyelinating milieu by lovastatin in mixed glial cultures stimulated with proinflammatory cytokines. Lovastatin-induced effects were reversed by cotreatment with mevalonolactone or geranylgeranyl-pyrophosphate, but not by farnesyl-pyrophosphate or cholesterol, suggesting that depletion of geranygeranyl-pyrophosphate is more critical than farnesyl-pyrophosphate in glial cells. These effects of lovastatin were mimicked by inhibitors of geranylgeranyl-transferase (geranylgeranyl transferase inhibitor-298) and downstream effectors {i.e., Rho-family functions (C3-exoenzyme) and Rho kinase [Y27632 (N-(4-pyridyl)-4-(1-aminoethyl)cyclohexanecarboxamide dihydrochloride)]} but not by an inhibitor of farnesyl-transferase (farnesyl transferase inhibitor-277). Moreover, activities of Rho/Ras family GTPases were reduced by lovastatin in glial cells. Corresponding with these findings, EAE animals exhibiting demyelination (on peak clinical day; clinical scores >/=3.0) when treated with lovastatin and aforementioned agents validated these in vitro findings. Together, these data provide unprecedented evidence that-like immune cells-geranylgeranyl-pyrophosphate depletion and thus inhibition of Rho family functions in glial cells by lovastatin promotes myelin repair in ameliorating EAE.

NADPH oxidase in human lung fibroblasts.

Reactive oxygen species produced by NADPH oxidase appear to play a role in the response of human lung fibroblast cells to rhinovirus infection. The purpose of the following studies was to characterize the NADPH oxidase components in these cells, to examine the effect of rhinovirus challenge on the expression of these proteins, and to confirm previous studies suggesting a role for p47-phox in the oxidant response to rhinovirus challenge. The results revealed that the NADPH oxidase components p47-phox, p67-phox, p22-phox, and NOX4 were expressed in lung fibroblast cells. In contrast, gp91-phox was not expressed in this cell line. Expression of p67-phox was upregulated by rhinovirus challenge. The functional role of NADPH oxidase in the rhinovirus-induced oxidant stress and elaboration of IL-8 was confirmed by detection of significant reductions in oxidant stress and IL-8 elaboration following transfection of the cells with antisense nucleotides to p47-phox. The lack of gp91- phox in cultured lung fibroblast cells, the induction of p67-phox by rhinovirus, and the confirmation of participation of p47-phox in rhinovirus-induced oxidant stress are significant findings of this study and form a basis for future investigations into understanding the mechanisms of the NADPH oxidase response to rhinovirus infection.

Regulation of gene expression associated with acute experimental autoimmune encephalomyelitis by Lovastatin.

The attenuation of experimental autoimmune encephalomyelitis (EAE) by Lovastatin (LOV) has now been well established. The present study was designed to explore the global effect of LOV treatment on expression of immune-related genes in lumbar spinal cord (LSC) during acute EAE by using Affymetrix DNA microarrays. LOV treatment demonstrated the limited infiltration of inflammatory cells into the LSC, and microarray analysis further validated those interpretations by demonstrating relatively less alteration in expression of immune response genes in LOV-treated EAE rats on peak clinical day and recovery vs. untreated EAE counterparts. There was significant change in expression of about 158 immune-related genes (including 127 genes reported earlier) in LOV-treated vs. untreated EAE (>1.5 or <-1.5 fold change; P

Respiratory reovirus 1/L induction of diffuse alveolar damage: a model of acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is a clinical syndrome that is characterized by diffuse alveolar damage usually secondary to an intense host inflammatory response of the lung to a pulmonary or extrapulmonary infectious or noninfectious insult. In this report we describe a unique animal model in which CBA/J mice infected with reovirus serotype 1, strain Lang develop ARDS. This model recapitulates the histopathological changes observed in human ARDS, which consists of the overlapping phases of exudation including the formation of hyaline membranes, regeneration, and healing via resolution and/or repair with fibrosis. While the consequences of a number of infectious and noninfectious insults in various animal systems have been developed as models of human ARDS, they are models of acute lung injury and are of short-term duration. Therefore, they do not recapitulate all of the clinical and pathological phases observed in human ARDS. Thus, study of the cellular and molecular factors involved in these distinct phases of the disease have been limited. Reovirus 1/L infection of CBA/J mice will allow investigations of the pathophysiology of ARDS as it progresses from the initial stages of edema and neutrophilia to fibrotic lesion development in late stages.